Method and system for determining and controlling a contrast opacification in an ultrasonic examination

ABSTRACT

A method and a system for using redundant wire bonds for increasing the reliability of ultrasound transducers are disclosed. An ultrasound transducer assembly having an ultrasound transducer, an integrated circuit, a plurality of wires, and a plurality of bond pads is provided. The integrated circuit includes enlarged lead pads for receiving redundant wire bonds. The ultrasound transducer includes a plurality of bond pads configured to receive the redundant wire bonds. Connecting wires, forming signal paths, connect the enlarged lead pads with the bond pads.

CROSS REFERENCE TO RELATED CASES

Applicant claims the benefit of Provisional Application Ser. No.60/476,139, filed 5 Jun. 2003.

The present invention relates generally to transducers. Morespecifically, it relates to a method and a system for using redundantwire bonds for increasing the reliability of transducers.

Connections between discrete components generally employ a singleconnection. Generally, the connection is a single wire formed fromcopper, gold, or aluminum.

In systems subjected to thermal-cycling conditions, wires are prone tofatigue failure. In many systems, stress resulting from thermal-cyclingconditions is directed along the axis of the wire resulting from amismatch of the coefficients of thermal expansion (“CTE”) among systemcomponents. A thermal stress to system components commences when thesystem is powered on. Therefore, it is an object of the presentinvention to provide a system for increasing the reliability ofultrasound transducers by reducing the average failure rate of theconnections between components in an ultrasonic system.

An ultrasound system having increased transducer reliability ishereinafter disclosed. In particular, the system includes an ultrasoundprobe with at least one ultrasound transducer and at least oneintegrated circuit assembly. Each integrated circuit assembly includesan integrated circuit, a plurality of connecting wires, and a connectingportion. A plurality of bond pads is disposed along at least one surfaceof the connecting portion and each bond pad is configured to receive atleast two wire ends. The integrated circuit has a plurality of lead padswhere each lead pad is configured to receive at least two wire ends.Each wire of the plurality of connecting wires is formed from anelectrically conductive material with first and second ends forconnecting each lead pad to the corresponding bond pad. The ultrasoundprobe is configured and adapted to receive at least one ultrasoundtransducer and at least one integrated circuit assembly.

Additionally, a method of increasing ultrasonic transducer reliabilityis disclosed herein where an integrated circuit assembly and anultrasound probe are provided. The integrated circuit assembly includesan integrated circuit, a connecting portion, and a plurality ofconnecting wires. The integrated circuit has a plurality of lead padswhere each lead pad is configured and adapted to receive at least twowire ends. The connecting portion has a plurality of bond pads, whereeach bond pad is configured and adapted to receive at least two wireends. The ultrasound probe has at least one ultrasound transducer. Theultrasound probe is configured and adapted to receive the at least oneultrasound transducer and at least one integrated circuit assembly.

The foregoing objects and advantages of the present invention may bemore readily understood by one skilled in the art with reference beinghad to the following detailed description of preferred embodimentsthereof, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a prior art connection between anintegrated circuit and a connecting portion;

FIG. 2 is a perspective view of an embodiment of an integrated circuitassembly according to the present invention; and

FIG. 3 is a side view of an ultrasound probe showing the location of theintegrated circuit assembly of FIG. 2 in the ultrasound probe.

Several embodiments of the present invention are hereby disclosed in theaccompanying description in conjunction with the figures. Preferredembodiments of the present invention will now be described in detailwith reference to the figures wherein like reference numerals identifysimilar or identical elements. As used herein, the term “distal” refersto that portion of the tool, or component thereof which is further fromthe user while the term “proximal” refers to that portion of the tool orcomponent thereof which is closer to the user.

In a typical prior art system, as shown in FIG. 1, an integrated circuit10 is disposed on a substrate 15 and includes lead pads 12 that aredimensioned to receive a single wire 14. Each wire 14 has first andsecond ends where a first end is connected to a lead pad 12 and a secondend is connected to a bond pad 16. A printed circuit board 18 includes aplurality of bond pads 16 for connecting components to the printedcircuit board 18. These single wire systems generally have a relativelyhigh average system failure rate.

The derivation of this solution requires using the “physics of failure”to understand the causative mechanism, and evoking reliabilityengineering principles. As discussed hereinabove, in the axis parallelto the wires, the displacement due to a positive temperature coefficientof expansion (“TCE”) is generally the greatest. When the probe assemblyheats up, i.e. when the system is powered on, the wire-loop from theintegrated circuit's lead pad to the bond pad on the printed circuitboard is cyclically stretched, thereby applying fatigue-inducing loadsthat break wires or joints.

The reliability of a one wire system is designated R1. According toreliability engineering, the reliability of a two wire redundant systemis determined by the formula 1-(1−R1)² and will typically be muchgreater than that of a one wire system. By way of example only, if asingle wire system has a reliability of R=0.5, then a similarlyconfigured two wire system has a reliability of R=0.75.

According to an embodiment of the present invention, an ultrasoundsystem for increasing ultrasound transducer reliability, and hence,overall system reliability, is hereinafter disclosed. Referring to FIG.2, a section of an integrated circuit 20 disposed on a correspondingsection of a substrate 32 is illustrated. Although only a portion of theintegrated circuit is shown in FIG. 2, it is within the scope of thepresent invention to use the entire “bare” integrated circuit (i.e. theintegrated circuit is not disposed within a surrounding package such asa dual-inline package, but is disposed on a substrate material). Anintegrated circuit assembly 40 according to the present inventionincludes the substrate 32, the integrated circuit 20, a plurality ofconnecting wires 24, 26, and the connecting portion 28. The integratedcircuit 20 is electrically coupled to a plurality of enlarged lead pads22 disposed near the outer perimeter of the integrated circuit 20located on the substrate 32. The plurality of connecting wires 24, 26,form a signal path, for electrically connecting each lead pad 22 with acorresponding bond pad 30 on the connecting portion 28. The number ofconnecting wires 24, 26 corresponds to the number of lead pads 22 andbond pads 30.

Advantageously, the connecting portion 28 will be a suitably configuredprinted circuit board having a plurality of bond pads 30 that correspondto the lead pads 22 of the integrated circuit 20. Other configurationsof the connecting portion 28 are envisioned including clusters orarrangements of bond pads disposed within the ultrasonic system.

Each wire 24, 26 is formed from a suitable electrically conductivematerial, such as copper, gold, or aluminum, and includes first ends24A, 26A and second ends 24B, 26B. By enlarging the lead pads 22, firstwire ends 24A, 26A are connected to each lead pad 22. Each bond pad 30corresponds to a respective lead pad 22 where each bond pad 30 isdimensioned to receive at least two second wire ends 24B, 26B. Secondwire ends 24B, 26B are connected to a respective bond pad 30, therebycompleting a signal path between the lead pad 22 and the bond pad 30.Signal data is transferred between the integrated circuit 20 and theconnecting portion 28 by the connecting wires 24, 26. Wires ends 24A,26A, 24B, 26B are connected to the lead pads 22 and/or the bond pads 30by conventional methods, such as wirebonding or soldering.

Referring to now to FIG. 3, a preferred embodiment of an ultrasoundsystem is shown. An ultrasound probe housing 60 includes a cavity 50, atleast one ultrasound transducer 45, and at least one integrated circuitassembly 40. The at least one ultrasound transducer 45 is disposed inthe distal region of the ultrasound probe housing 60. The cavity 50 isdisposed along a longitudinal axis of the ultrasound probe housing 60and is positioned adjacent to and rearward of the at least oneultrasound transducer 45. The at least one integrated circuit assembly40 is configured and dimensioned to fit within the cavity 50. It isenvisioned that the ultrasound probe housing 60 is configured andadapted to include a plurality of ultrasound transducers 45 with acorresponding number of integrated circuit assemblies 40. The pluralityof ultrasound transducers 45 may be configured in various arrayconfigurations, such as one-dimensional or two-dimensional matrixarrays. Additionally, the ultrasound probe housing 60 includes circuitryfor communicating with the integrated circuit assembly 40 and/or theultrasound transducer 45.

It is preferred that at least the critical signals of an ultrasoundtransducer include redundant wire bonds in accordance with the presentinvention. These critical signals include clock signals, data lines,control lines, and power supplies.

In another embodiment, an ultrasound system having increased reliabilityis disclosed where at least one integrated circuit includes a pluralityof enlarged lead pads. Each lead pad is configured and dimensioned toreceive the first ends of at least two connecting wires. An ultrasoundprobe housing includes a corresponding number of bond pads wherein eachbond pad is configured and dimensioned to receive the second ends of atleast two connecting wires. The bond pads are disposed in the ultrasoundprobe housing. Connecting wires are disposed in the ultrasound probehousing for transferring signals to and from the integrated circuit. Asignal path is formed by the pair of connecting wires between the leadpad and the respective bond pad. Furthermore, the number of connectingwires corresponds to the number of lead pads and bond pads included inthe ultrasound system.

A method of increasing reliability of an ultrasound transducer assemblyis hereinafter disclosed. According an embodiment of the presentinvention, an ultrasound probe housing is provided that includes atleast one ultrasound transducer. The ultrasound probe housing isconfigured and dimensioned to receive at least one integrated circuithaving enlarged lead pads. A plurality of connecting wires is furtherincluded wherein the number of connecting wires corresponds to thenumber of lead pads of the integrated circuit and the bond pads of theultrasound assembly. The connecting wires have first and second ends.Each lead pad of the integrated circuit is dimensioned to receive thefirst ends of at least two connecting wires. Correspondingly, the bondpads of the ultrasound assembly are configured to receive the secondends of at least two connecting wires. A signal path between a lead padand the corresponding bond pad is formed by at least two wires. Thefirst ends of the signal path are connected to the lead pad. The secondends of the signal path are connected to the bond pad. The ends of thesignal path may be joined to the respective lead pad and/or bond pad byconventional methods, such as wirebonding or soldering.

The described embodiments of the present invention are intended to beillustrative rather than restrictive, and are not intended to representevery embodiment of the present invention. Various modifications andvariations can be made without departing from the spirit or scope of theinvention as set forth in the following claims both literally and inequivalents recognized in law.

1. An ultrasound system having increased transducer reliability, theultrasound system comprising: an ultrasound probe including anultrasound transducer; at least two wires, each wire having a first endand a second end; at least one connecting portion configured anddimensioned to fit within the ultrasound system, the connecting portionhaving a plurality of bond pads, each bond pad configured anddimensioned to receive respective first ends of the at least two wires;and at least one integrated circuit disposed in the ultrasound systemhaving a plurality of lead pads, each lead pad configured anddimensioned to receive respective second ends of the at least two wires.2. The ultrasound system of claim 1, wherein the at least one integratedcircuit is disposed in the ultrasound probe.
 3. The ultrasound system ofclaim 1, wherein the at least one connecting portion is a printedcircuit board.
 4. A method for increasing ultrasound transducerreliability comprising the steps of: providing an ultrasound probehaving an ultrasound transducer; providing at least two wires, each wirehaving first and second ends; providing at least one connecting portionconfigured and dimensioned to fit within the ultrasound probe and havinga plurality of bond pads, each bond pad configured and dimensioned toreceive respective first ends of the at least two wires; providing atleast one integrated circuit disposed in the ultrasound probe having aplurality of lead pads, each lead pad configured and dimensioned toreceive respective second ends of the at least two wires; connecting thesecond ends of the at least two wires to a respective one of the leadpads of the integrated circuit; and connecting the first ends of the atleast two wires to a respective one of the bond pads of the connectingportion.
 5. The method of claim 4, wherein the at least one connectingportion is a printed circuit board.
 6. An ultrasound system havingincreased reliability comprising: an ultrasound probe including anultrasound transducer; at least one connecting portion configured anddimensioned to fit within the ultrasound probe and having a plurality ofbond pads; at least one integrated circuit disposed in the ultrasoundprobe having a plurality of lead pads; and at least one connector forconnecting a respective bond pad with a respective lead pad, theconnector including at least two wires.
 7. The ultrasound system ofclaim 6, wherein the at least one connecting portion is a printedcircuit board.
 8. An ultrasound system having increased transducerreliability, the ultrasound system comprising: an ultrasound probeincluding an ultrasound transducer; at least two wires, each wire havinga first end and a second end; and at least one integrated circuitdisposed in the ultrasound system having a plurality of lead pads, eachlead pad configured and dimensioned to receive respective second ends ofthe at least two wires.
 9. The ultrasound system of claim 8, furtherincluding at least one connecting portion configured and dimensioned tofit within the ultrasound system, the connecting portion having aplurality of bond pads, each bond pad configured and dimensioned toreceive respective first ends of the at least two wires.
 10. Theultrasound system of claim 9, wherein the at least one integratedcircuit is disposed in the ultrasound probe.
 11. The ultrasound systemof claim 8, wherein the ultrasound probe further includes a plurality ofbond pads, each bond pad configured and dimensioned to receiverespective first ends of the at least two wires.
 12. The ultrasoundsystem of claim 11, wherein the at least one integrated circuit isdisposed in the ultrasound probe.
 13. The ultrasound system of claim 10,wherein the at least one connecting portion is a printed circuit board.14. A method of increasing ultrasound transducer reliability comprisingthe steps of: providing an ultrasound probe having an ultrasoundtransducer; providing at least two wires, each wire having first andsecond ends; and providing at least one integrated circuit disposed inthe ultrasound system having a plurality of lead pads, each lead padconfigured and dimensioned to receive respective second ends of the atleast two wires.
 15. The method of claim 14, further comprising the stepof: providing at least one connecting portion configured and dimensionedto fit within the ultrasound system, the connecting portion having aplurality of bond pads, each bond pad configured and dimensioned toreceive respective first ends of the at least two wires.
 16. The methodof claim 15, wherein the at least one integrated circuit is disposed inthe ultrasound probe.
 17. The method of claim 14, wherein the ultrasoundprobe further includes a plurality of bond pads, each bond padconfigured and dimensioned to receive respective first ends of the atleast two wires.
 18. The method of claim 17, wherein the at least oneintegrated circuit is disposed in the ultrasound probe.
 19. The methodof claim 16, wherein the at least one connecting portion is a printedcircuit board.